Conventionally, a plate provided with wells has been used to select particles according to sizes and shapes (hereinafter, these are referred to as shapes in some cases) in various fields. A user observes the particles in a state held in the wells of the plate and selects and collects only the particles of a predetermined shape. Larger articles to be selected include tablets, capsules and granulated granules and smaller ones include bio-based cells used in the fields of bio-related technology and medicine. For example, the user can make deviations of test conditions in various tests using cells smaller by selecting the cells and making the shapes thereof uniform. The selected cells can be subjected to high-throughput screening (HTS) and the like.
There are various methods for collecting subjects held in wells. For example, a method for sucking and collecting subjects using a push-button type suction pipette provided with a suction tip or a suction nozzle on its tip is adopted in a biochemical experiment or the like. If specimens vulnerable to dryness such as cells are subjects, an operation is preferably performed in liquid to prevent the drying of the subjects. In the case of sucking the subjects in the liquid, a liquid flow is generated from a suction port into a suction path to suck the subject in the well by simultaneously sucking the liquid around the well.
However, in a state where a tip part of the suction nozzle is inserted in the well, an inner wall or an inner bottom part of the well and the tip part of the suction nozzle may be held in close contact to block a flow passage for the liquid. In this case, there is a problem of being unable to suck the subject held in the well since the liquid around the well cannot be sucked.
In view of such a problem, a container for sucking/discharging a fixed quantity without closing a suction port is disclosed in International Publication No. 97/5492. A gap portion having a narrower width than an opening of a tip part of the suction port is formed on an inner bottom part of the container of International Publication No. 97/5492. A well formed with a groove on the outer periphery is disclosed in Japanese Unexamined Patent Publication No. 2007-326072. The well of Japanese Unexamined Patent Publication No. 2007-326072 is formed with the groove having such a width that fine specimens cannot be fitted into the groove.